1. Field of the Invention
The apparatus and method of the present invention relates to equipment for installing sections of sand screens into a well bore. More particularly, the present invention relates to a hydraulically powered screen table mountable on the rotary table which allows a length of sand screen to be released into the hole when there is an emergency on the oil rig.
2. General Background of the Invention
In the general operation of oil equipment, during the recovery of the hydrocarbons from the well, after hydrocarbons are found, one part of the process is to lower sections of pipe which are comprised of layers of screen material, known as sand screens, so that when the oil is brought up to the surface through the pipe, the oil is filtered through the screen and into the interior of the pipe in order to remove all of the sand impurities of the like from the oil. Of course, in order to place the sand screen down the bore hole of the oil well, sections of sand screen must be interconnected end to end, as with normal sections of pipe during the drilling or recovery of oil. This is accomplished by the use of a screen table.
A screen table is a device which is placed onto the rotary table above the opening in the rig floor. A section of sand screen is lowered through a central opening in the screen table, and into the well bore. The screen table includes a pair of opposing plates which engage the wall of the sand screen below the box end of the section of sand screen, which allows the sand screen to hang from the screen table by the large box end. While in place on the screen table a next section of sand screen is lowered onto the section in place and rotatably engaged to it. Once that is done, the screen table plates are manually pulled away from one another while the section of sand screen is held in place above the rig floor, and the next section of sand screen pipe is lowered and the process is repeated until sufficient number of sections of sand screen are in place down the borehole.
One of the problems in this operation is that during this placement of sand screens end to end, the weight of the entire length of sand screens down hole becomes extremely heavy. Therefore, when the plates are engaged against the wall of the sand screen, and the sand screen string is “hanging” in the well bore. Should there occur a problem down the hole such as a kick, the plates cannot be manually pulled away from the sand screen since the weight of the pipe does not allow the manual manipulation of the plates, and the sand screen string is not allowed to drop down into the borehole.
This could cause a serious problem, since normally, when a kick occurs, the blowout preventors below the rig floor are immediately closed so that any pressure from the kick remains within the bore hole and does not reach the rig. However, because the sand screen sections are not rigid, since they are comprised of layers of soft filter material, the blowout preventors cannot sever the string, and may not be fully closed. If this should occur, the pressure will then reach the rig which could have catastrophic results. Therefore, to avoid this eventuality, it is imperative that the sand screen be allowed to be released from the screen table, and fall into the borehole to a level below the blowout preventor stack, so that the blowout preventors fully close and capture the kick downhole. Therefore, there is a need in the industry for a device which would allow the plates to be disengaged from the wall of the sand screen string so that the string of sand screens can be allowed to drop into the hole for the safety of the workers on the rig.
Applicant is submitting herewith an Information Disclosure Statement which includes the following patents which were found in the prior art.
The following U.S. Patents are incorporated herein by reference:
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